PV Line tap on two different panels

[Caleb Bydone]

I have an inspector that is failing our PV interconnection method because the homeowner has two separate panels that are being supplied by a single 320A meter. Our PV system is interconnected via piercing connectors on one set of SE cables, and not across both panels. One thing that I can see as a rebuttal to the inspector is that he's a nut and our parrallel source cannot be interconnected onto a single phase across two different panels. (Phase A of panel A, and Phase B of Panel B) Is there anything else in the NEC that I can provide the inspector?

 

[ggunn]

I have an inspector that is failing our PV interconnection method because the homeowner has two separate panels that are being supplied by a single 320A meter. Our PV system is interconnected via piercing connectors on one set of SE cables, and not across both panels. One thing that I can see as a rebuttal to the inspector is that he's a nut and our parrallel source cannot be interconnected onto a single phase across two different panels. (Phase A of panel A, and Phase B of Panel B) Is there anything else in the NEC that I can provide the inspector?

As always, ask the inspector (in the most respectful way possible) to provide specific code references for each perceived violation. You cannot use code to fight this if he won't tell you specifically what articles it it isn't compliant with.

"I don't like it" isn't a code reference.

 

[jaggedben]

Maybe look at the parts of 230 that deal with multiple sets of service entrance conductors supplying multiple service disconnects. Try to explain that what you're doing is normal for such services and PV doesn't make it different. You're just creating a third set of service entrance conductors. See in particular 230.40 Exception 2.

Also, if you did what he seems to be asking, I'm guessing there's a good chance you'd be violating the sections on parallel conductors, especially their being the same length and 'joined on both ends'. 310.10(H)

(2017 NEC references)

 

[synchro]

300.3(B) says that conductors of the same circuit shall be contained within the same cable. So you can't attach one phase of your PV circuit to one SE cable and attach the other phase to another SE cable, if I understand what the inspector was talking about..

 

[GerryB]

300.3(B) says that conductors of the same circuit shall be contained within the same cable. So you can't attach one phase of your PV circuit to one SE cable and attach the other phase to another SE cable, if I understand what the inspector was talking about..

Sounds like the OP connected to one SEU, but the EI wants him to hit both? I thought in this case you could do what the OP did but you need main breakers in those panels also if they are main lug.

 

[ggunn]

Sounds like the OP connected to one SEU, but the EI wants him to hit both? I thought in this case you could do what the OP did but you need main breakers in those panels also if they are main lug.

If the panels are service entrances then they do not need main breakers when you connect PV on the line side. The available current to them is already virtually unlimited; the PV system makes no difference.

What the inspector is asking him to do (connect on the line side of both panels) is incorrect. Connecting on the line side of either is already connecting to them both; the service conductors between the meter and the panels is a single node.

One thing, though; if the panels are indeed MLO service entrances, the maximum number of breakers in both panels combined cannot exceed six. If there are more, then one or both the panels indeed need main breakers no matter if PV is there or not.

 

[GerryB]

If the panels are service entrances then they do not need main breakers when you connect PV on the line side. The available current to them is already virtually unlimited; the PV system makes no difference.

What the inspector is asking him to do (connect on the line side of both panels) is incorrect. Connecting on the line side of either is already connecting to them both; the service conductors between the meter and the panels is a single node.

One thing, though; if the panels are indeed MLO service entrances, the maximum number of breakers in both panels combined cannot exceed six. If there are more, then one or both the panels indeed need main breakers no matter if PV is there or not.

I was thinking of a 320 amp metermain with two 200 amp breakers in it, if that is different.

 

[jaggedben]

I was thinking of a 320 amp metermain with two 200 amp breakers in it, if that is different.

While the existing service entrance conductors would need overload protection per Article 230, the exact details are essentially irrelevant to the question. Regardless of the exact configuration, there would never be a reason for a supply side PV connection to terminate in more than one place. Unless the OP mis-described the situation, the inspector has some fundamental misunderstanding of what he's looking at.

 

[ggunn]

While the existing service entrance conductors would need overload protection per Article 230, the exact details are essentially irrelevant to the question. Regardless of the exact configuration, there would never be a reason for a supply side PV connection to terminate in more than one place. Unless the OP mis-described the situation, the inspector has some fundamental misunderstanding of what he's looking at.

From his post #7 it looks like the conductors leaving the meter can may be individually protected at 200A, so what he is looking at is a load side tap, not a line side tap as I was thinking. If that is the case then tapping both sets of conductors into the panels would really be a bad thing as it would connect the load side conductors from two separate OCPDs. Tapping one line of one panel and the other line of the other is just insane, IMO, and sounds like a cowboy improvisation. Perhaps I misunderstood

In this scenario, though, if he taps the conductors going into a panel he will need a main breaker in that panel unless the panel busbar and the conductors between the tap and the panel are rated for the OCPD from the meter can plus 125% of the maximum rated inverter current. 705.12(B)(2)(1) in the 2017 NEC or 705.12(D)(2)(1) in prior code.

 

[jaggedben]

Post 7 was not by the OP. I think the OP was pretty clear it was line side. Regardless, nothing in the OPs question was about overcurrent protection. And I can't think of any situation, in any application, in which code allows, let alone requires, parallel connection to two different circuits.

 

[ggunn]

Post 7 was not by the OP. I think the OP was pretty clear it was line side. Regardless, nothing in the OPs question was about overcurrent protection. And I can't think of any situation, in any application, in which code allows, let alone requires, parallel connection to two different circuits.

Me neither.